Drill bit and shank



Nov. 14, 1939. L. SALTZER 2,180,120

DRILL BI T AND SHANK Fi led Dec. '4, 1957 INVENTOR Louis SaZizeJ" JOa I BY @mg mm ATTORNEY Pamela. 14, 1939 UNITED STATES PATENT- OFFICE 1 Claim.

This invention relates in general to rock drilling equipment and in particular is directed to a drill bit and shank and the means for removably securing the same together for use.

- The drill bits now used are tapped for threaded engagement with one end of the drill rod. Such a threaded connection is however unsatisfactory to the extent that it is difllcult to keep the drill bit tight on the rod, and the threads on the rod and within the bit are subject to such strain that they often strip necessitating rethreading of the rod or replacement of the bit whichever is damaged. Although the rods can be rethreaded, the bits cannot be retapped. Thus, there is a substantial and undue expense incurred to maintain drilling equipment in working order.

In view of the above objectional features of a threaded connection between a drill bit and rod, I have constructed, and it is my principal object to provide, connecting means which will be strong and durable and will not require repeated replacement of bits and repair of rods.

A further object of the invention is to provide means whereby quick attachment of bit and rod may be accomplished, the bit held securely in place on the rod during a drilling operation, and the bit easily and readily removed from the rod.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be exceedingly effective for the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claim.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Figure l is an elevation of my improved drill bit and shank; the socket of the bit being in section and the shank partially inserted therein.

Figure 2 is a similar view but with the shank fully engaged within the socket.

Figure 3 is an end view of a four-sided drillrod shank.

Referring now more particularly to the characters of reference on the drawing, and particular ly at present to Figs. 1 and 2, thenumeral i indicates a drill bit provided as usual at one end with outwardly projecting cutting teeth 2. The bit at the base is formed with a socket 3, such socket being multi-sided and in the present instance hexagonal. The socket 3 is formed with a very slight inward taper from the outer end to a point. indicated at 4. close to but spaced from the bottom 5 of the socket. From point 4 to bottom 5 the socket is tapered outwardly at 8 and to a greater degree or at a sharper angle than the inward taper of the remainder of the socket as described above, so that an enlargement is formed in the base of the socket at its inner end.

The cooperating drill rod, shown at 1, is provided with an enlarged portion 8 which forms a shoulder 9 spaced from the adjacent end of the rod a distance equal to the depth of socket 3 in the bit. The drill rod from shoulder 9 to the adjacent rod end provides a shank ill for entry into drill bit socket 3. Certain sides of the shank ID are formed symmetrical with and of the same size as all the sides of socket 3; these shank sides thus tapering from shoulder 8 to a. point I I close to the outer end thereof and then tapering outwardly from point II to said end, forming an enlargement to fit the enlarged bore portion.

The outer end of shank I0 is chamfered as at I 2 to facilitate initial entry of the shank into socket 3. The shank is deeply notched or slit diametrally, as at I3, from its outer end to a point approximately centrally of the shank length. This notch or slot extends between the other opposed sides of the shank other than said certain ones, and which, while they may have the initial taper, do not have the diverging taper at their outer ends, so that the width of these sides at any point in their length is no greater than the distance between opposed points 4 of the socket bore.

Beveled depressions l4 adjacent the inner end of the notch on both sides of the shank prevent fracturing about the base of the notch. The width or diameter of the socket bore at its outer end is approximately the same as or not-less than the width of the shank at the base of the chamfer l2, so that the socket may be initially slipped over the shank without restraint or bind- After the socket has been engaged with the shank by hand as far as possible, the bit is struck on its outer end. This causes the shank, as the relatively large divergingly tapered portion thereof moves along the converging taper of the socket, to be squeezed or compressed, as indicated in Fig. 1, the shank being of course of resilient steel as usual. As soon as the outer end of the shank passes the point 4 and the adjacent portion thereof approaches the base 5 of the socket, the compressing pressure is relieved, and the shank expands into and fits the outwardly tapering portion 6- of the socket. The drill bit is thus firm- 1y held in place on the shank, both against rotation as well as longitudinal displacement.

To remove the bit. it is only necessary to strike the same a few sharp blows at the base of the socket, in the direction of the opposite end of the bit, until the enlarged taper portion of the shank has been moved outwardly past point 4.

The same result may be obtained with a foursided or square drill rod and shank as indicated in Fig. 3. In this case, the shank Illa has the slot l3a cut therethrough parallel to a pair of the sides oi the shank, and these sides only have the outwardly tapering end portions corresponding to those between the point II and the outer end of the shank in the type shown in Figs. 1 and 2, and here indicated at T. The bit used with this tom of drill rod of course has a square socket to correspond.

From the foregoing description it will be readily seen that I have produced such a device as substantially iulfllls the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device,

still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention as defined by the appended claim.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

In combination, a drill rod having a bit engaging shank of resilient metal and a drill bit having a socket to receive and cooperate with the shank in non-tuming relation; said socket tapering gradually in size from its outer end to a point short of its inner end and then increasing in size from said point to its inner end, the socket at said inner end being no greater in size than at its outer end and the shank being shaped and of a size to conform to the socket from end to end thereof, the shank being split from its outer end for a distance suflicient to enable the shank at its point of greatest width to be contracted so as to pass the point oi least width of the socket.

LOUIS SAL'IZER. 

